Is bamboo fabric antibacterial?

There are many claims about bamboo fabric, one of which is that it's antibacterial. But is there any scientific evidence to support this? I've looked at two different scientific studies which specifically cite bamboo viscose (which in reality is just a viscose, also known as rayon in the USA) and summarised the findings for you here.

Why does a fabric being antibacterial (or antimicrobial) matter?

Let's start with why a fabric being antibacterial could make a difference to you. In a nutshell, it could help you smell less when you sweat.

Why do we smell, especially when we sweat?

Why do we sometimes get smelly and why do clothes pong so much after a heavy session in the gym? It's all to do with your sweat and how this reacts to your skin. Your body has two main types of sweat glands (eccrine glands and apocrine glands), and they produce two different types of sweat. Both types of sweat are odourless; sweat only starts to smell when it combines with bacteria found on your skin. This can be especially unpleasant in your armpits and groin.

If it's the bacteria found on our skin, combined with your sweat, which causes you to smell it follows that any material which helps to inhibit bacterial growth should help you to be less smelly.

What does the research say about antibacterial (or antimicrobial) materials?

Research has found that some fabrics cause bacteria to multiply while other fabrics seem to help to destroy some of the bacteria.

In this study, seven fabrics were tested against five different bacteria, and the results can be seen in this table.

From my understanding of these results, and from what is indicated by the conclusion of the paper, the largest bacteria growth was in polyester and wool. The largest inhibition was seen on viscose and fleece textiles. According to these results, viscose did not permit any growth of bacterial species tested. Wool*, on the other hand, supported the growth of almost all bacteria. Nylon showed very selective bacterial growth.

*This study is in conflict with what people report about merino wool. Merino wool is said to have antibacterial properties due to the presence of lanolin and keratin.

So, in essence, what this study says is that when you sweat, and it combines with your skin's bacteria if you are wearing polyester or wool it's likely to increase the number of bacteria and smell more. However, if you are wearing viscose or fleece, it may help decrease the number of bacteria and hence smell less.

What's this got to do with bamboo fabric? Bamboo fabric is a type of viscose (also called rayon in the USA), so wearing this fabric should help with any smell issues.

This study notes that further research is needed to confirm the results on the absence of bacterial growth on viscose and this needs to be taken into account. It recognises that "if bacterial growth is indeed impeded on these fibre types, viscose is a good choice as bacterium- and odor-preventing textile in functional clothes."

This study, published in the Journal of Family Ecology and Consumer Sciences, has also shown that bamboo viscose and generic viscose fabrics appear to be antimicrobial.

This study looked at whether viscose sourced from bamboo had superior antibacterial qualities over other viscose fabrics and cotton. There have been claims that bamboo viscose fabrics have a unique antibacterial quality due to an antimicrobial bio-agent called “bamboo kun” which is found naturally in living bamboo fibre. This kun supposedly makes bamboo a naturally antibacterial, antifungal and odour resistant fibre. However, there has been some debate about whether this 'bamboo kun' property is lost in the processing of bamboo into bamboo viscose (or rayon) fabric.

This study found that bamboo viscose and other viscose both demonstrated antibacterial qualities when compared to cotton. It found that viscose from bamboo and other viscose fabrics performed the same; sourcing from bamboo did not show any superior antimicrobial properties over other viscose fabrics. Cotton was not found to possess these antibacterial qualities.

So, according to this study, bamboo viscose does have antibacterial qualities although this also applies to all viscose fabrics.

In our own smell tests...

We've also conducted our own experiment, which we call our 'smell test'. It is a simple test where we wear the same undershirt and give it a 'smell test' at the end of the day to see how many days it could go before it started to 'pong'.

In our (very subjective) tests we found that the bamboo viscose undershirt would last for about three days, whereas a cotton T-shirt would start to smell by the end of the first day. Obviously, this was in no way a scientific experiment, but it is in line with the results of the above two studies.

Our conclusion?

It appears, from the two scientific studies, that fabrics made from viscose do inhibit the growth of bacteria and hence could be less smelly in situations where you sweat. Conversely, polyester and wool promote bacteria growth and could make you smell more quickly.

Viscose is an ideal fabric for wearing next to your skin. Not only does it feel amazingly soft, lightweight and breathable, but it also stays fresher for longer. That's why we choose it for our undershirts.